Adolescent Adult Amputation, Surgical Antineoplastic Agents--therapeutic use Bone Neoplasms--pathology Cell Division Child Clinical Trials as Topic Doxorubicin--therapeutic use Drug Therapy, Combination Female Humans Leucovorin--therapeutic use Lung Neoplasms--pathology Male Methotrexate--therapeutic use Neoplasm Metastasis Osteosarcoma--pathology Prognosis Radiotherapy, High-Energy Time Factors